1. Technical Field of the Invention
The present invention relates to an information holding method for holding predetermined information on a sheet material such as a recording paper.
2. Related Art
Recently, together with an improvement in the performance of copiers and printers and an improvement in processing performance of personal computers and the like, it becomes possible to highly precisely copy an image recorded on an original. As a result, it becomes possible to form a high quality image to the extent where the original and the copy are hardly distinguishable.
Meanwhile, the capability of copying an image which makes it difficult to distinguish an original and a copy, increases the likelihood of copying paper currencies and securities as well as various documents including passports, various title deeds, and various certificates. It has been desired to establish technology whereby it is possible to highly accurately distinguish whether it is true or not that various documents are the original.